The present invention relates to a castor structure, and in particular to a self-orientatable twin castor of the type which comprises a pair of coaxial wheels.
Twin castors are constituted by a pair of wheels rotatably mounted on a pivot.
The pivot is horizontally supported by a tubular hub of a support which comprises a semi-cylindrical wall defining a casing or fairing-like structure which covers the upper part of the castor. A blind hole is defined in the semi-cylindrical wall, is open upward and acts as rotation seat for a vertical self-orientatable pivot intended to be inserted and fixed in an accommodation of the piece of furniture to which the castor is to be applied. The hub is internally provided with coupling elements for a collar provided externally on a hollow tang which protrudes coaxially from the respective wheel.
In conventional twin castors, the support is made of plastics or metal.
Castors in which the support is made of plastics are more economical than metallic ones. However, metallic supports are stronger and are used when the castor is designed to have a particular aesthetic appearance, such as chromium plating, brass coating, etc.